[pgpool-general: 4722] Re: Problem shutting down interfaces

[Guptesh Kumar]

Hi Ricardo,

I am facing a similar issue -

Node 1 : Master pgpool, Master Postgresql
Node 2 : Slave Pgpool, Slave Postgresql

When I pull out the power cable of  master node(Node 1), the Slave watchdog
promotes itself to Master correctly. But the pgpool in NOW master node(Node
2) neither disconnects the Node 1 Postgresql  from the pool nor it promotes
the Node 2 postgresql as Master(failover does not happen). All my DB
connection hangs.

I tried various values for health_check parameters but none of them helped.

Softwares Used are -
pgpool-II-pg94-3.5.2-1pgdg.rhel7.x86_64
postgresql94-server-9.4.7-1PGDG.rhel7.x86_64

Thanks & Regards,
Guptesh


On Tue, May 10, 2016 at 11:36 PM, Ricardo Larrañaga <
ricardo.larranaga at gmail.com> wrote:

> Hi guys:
> I have been working on this a little bit, and i encounter this problem
> (running pgpool 3.5.2 on a 2 node cluster with streaming replication, if i
> shut down the interface of the slave, pgpool on the master hangs the
> connections). And i realize that the problem only happens when i shut down
> the interface. If i either shut down the processes or use the firewall to
> block backend communication, pgpool reacts properly.
>
> Does anyone have experience with this or have a 2 node cluster with
> streaming replication to test it. I am trying to identify what makes the
> setup hang, since shutting down the interface is the best way i have to
> simulate a node crash. When i shut down the interface, both postgres and
> pgpool loose connection, but this is a valid scenario that could happen in
> real life (when the whole server crashes).
> Thanks a lot.
> Regards
>
>
> On Thu, May 5, 2016 at 4:55 PM, Ricardo Larrañaga <
> ricardo.larranaga at gmail.com> wrote:
>
>> Hello guys:
>> I am running pgpool 3.5.2 in a 2 node cluster with postgresql-9.5 in
>> master-slave and streaming replication mode.
>>
>> I have been testing failover and failback for a while. While doing
>> failover by shutting down the processes, everything looks fine.
>>
>>
>> The one test that is failing is when i shutdown the interface of one node.
>> Right now i am shutting down the interface of the slave node (both pgool
>> slave and postgresql slave).
>>
>> The problem i am running into is that after doing this, all connections
>> to my database (through pgpool) hang. i am testing it with psql, and psql
>> just hangs and does not give me an output. When i bring the interface of
>> the slave back up, and try to connect to psql again, it looks like pgpool
>> never marked the postgresql node as disconnected.
>>
>> I tried both with and without health check, and also tried with different
>> values of health_check_timeout. my connect timeout value is default (10
>> seconds).
>>
>> Any one has encountered this issue? I just dont see pgpool attempting to
>> do any failover. Pgpool is still running though, i can see the logs still
>> comming. I just never see an error.
>>
>> I am NOT using interface monitoring, and i would prefer not to use it.
>>
>> Any pointers on how could i troubleshoot this?
>> Thanks.
>> Regards
>>
>>
>
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